It is well known in the art that hydrogen peroxide, carbamide peroxide (urea peroxide) and other peroxides can be used as bleaching agents in the formulation of tooth-bleaching gels. The prior art also discloses that carboxypolymethylene (Carbopol), poloxamer (Pluronic), and cellulosic gums, as well as other thickeners, can be used as the gelling agent in the preparation of peroxide gels.
Much attention has been paid in the art to controlling the pH of such compositions in use in order to optimize bleaching performance.
Thus, US2006251591 discloses dental compositions and methods for bleaching teeth directed towards hydrogen peroxide-containing compounds that are maintained at a substantially constant pH range of 6.0-10.0 during the tooth-bleaching procedure in the presence of a calcium chelating agent.